Prepare the marinade and glaze: In a large
nonaluminum bowl, combine all the ingredients and whisk to mix well.
Taste for seasoning.

Carefully separate the skin from the hens by slipping your fingers
gently under the skin and loosening it, yet keeping it attached to
the birds. Place the hens in the bowl with the marinade. Massage the
marinade underneath the skin, being careful not to tear the skins.
Rotate the hens until they are completely covered with the marinade.
Cover and refrigerate for 2 to 4 hours

Preheat the oven to 425 degrees. Line a large jelly-roll pan or
roasting pan with aluminum foil. Remove the hens from the marinade
and place them in the lined pan. Roast the hens, basting with the
pan juices every 15 minutes for 40 to 45 minutes, or until the
juices run clear when a thigh is pierced and the skin is golden
brown.

Place the hens on a serving platter or individual plates and garnish
with the orange slices.